1 86 Bugs, Cicadas, Aphids, and Scale-insects 



secrete no wax, but have the body-wall of the dorsum strongly chitinized, 



and usually very convex, so that it forms 

 a strong rigid protecting shell; finally the 

 females of the third (and largest) group are 

 the so-called armored scales, which in the 

 adult stage are degenerate creatures without 

 distinct body segmentation, without antennae, 

 eyes, and legs, thus being incapable of 

 locomotion; they form a flattish or convex 

 dorsal scale of secreted wax and of the cast 

 skins or exuviae of the body. 



In all the groups the males (Figs. 252 and 

 253) are very different in appearance from the 

 females, being minute fly-like creatures with 

 a single pair of wings, a pair of long antennae, 

 and a plump, soft, little body, usually 

 terminating in a single needle-like process or 

 in a pair of long waxen hairs. Males are 

 not yet known for some of the species. 



FIG. 253. The fluted or cottony 

 cushion-scale, Icerya purchasi, 

 winged male and wingless 

 female with fluted waxen egg- 

 sac (es). (After Jordan and 

 Kellogg, much enlarged.) 



Familiar examples of the first group are the mealy-bugs (Dactylopius sp.) 

 of greenhouses and gardens, soft-bodied scales, bearing projecting rods 

 and threads of white wax of varying length, and rather prettily arranged. 

 A more famous and interesting member of this group is the fluted or cottony 

 cushion-scale, Icerya purchasi (Fig. 253) (so called because of the beautiful 

 fluted white waxen egg-sac secreted by the female), which once threatened 

 to destroy all the orange-groves of California, but was brought to bay by 

 a little red and black ladybird-beetle, Vedalia cardinalis (Fig. 254), brought 

 from Australia for this very purpose. In 1868 some young orange-trees 

 were brought to Menlo Park (near San Francisco) from Australia. These 

 trees were undoubtedly infested by the fluted scale, which is a native of 

 Australia. These scale immigrants throve in the balmy California climate, 

 and particularly well, probably, because they had left all their native enemies 

 far behind. By 1880 they had spread to the great orange-growing districts of 

 southern California, five hundred miles away, and in the next ten years 

 caused enormous loss to the growers. In 1888 the entomologist Kcebele, 

 recommended by the government division of entomology, was sent at the 

 expense of the California fruit-growers to Australia to try to find and send 

 back some effective predaceous or parasitic enemy of the pest. As a result 

 of this effort, a few Vedalias were sent to California, where they were zeal- 

 ously fed and cared for, and soon, after a few generations, enough of the little 

 beetles were on hand to warrant trying to colonize them in the attacked 

 orange-groves. With astonishing and gratifying success the Vedalia in a 



